The present invention is for the kind of power machines, engines, pumps or compressors which have two or more pistons which work against each other and preferably have a common combustion space within a stationary cylinder and where the power is transmitted to or from a rotating movement without an intermediate crankshaft.
Independent of wether the machine works as an engine compressor or pump there is a need to cool the cylinder bore. For certain applications such as engines for lawn-mowers and power saws these must be cooled by air as it in practice is very difficult or impossible to arrange a water cooling system.
In combustion engines the transmission of force from a to and fro (i.e., reciprocating) motion to a rotating motion generally is by means of some kind of crankshaft or the like. In certain cases however crankshafts are less suitable, and this is especially the case when to and from motions with different, often directly opposite directions together shall be transmitted into a rotating motion. Especially this is the case by that kind of power machines e.g. combustion engines, compressors or pumps, where two pistons at the same time work against each other in a common cylinder bore. In these cases the use of crankshaft bring with them complicating mechanical designs to put together the power from the two pistons into one common rotating motion. The transmission of force between a to and from motion and a rotating motion may instead take place using a ball bearing which runs in several tracks and includes a ball which is surrounded by a ball holder which is attached to one piston rod or the like member for each ball for transmission of the linear motion into rotating motion. It is also possible to exchange the balls for other means with corresponding functions, for example rolls or pins which roll or slide in the tracks.
One such device has two parallel plane discs both a stationary disc and one relatively thereto rotating disc. In a cylinder positioned centrally relative to the disc there are two pistons which are working pistons of a combustion engine, and have a common combustion space. Fixed to each piston there is a piston rod which at its opposite end has a holder means for the ball by which the force from the to and fro motion is transmitted to the rotating disc. The balls also serve as bearings between the stationary disc and the rotating disc. The rotating disc is mounted onto a holder which in turn is mounted onto an outgoing shaft from which the rotating force is taken for use for various driving purposes. The balls can move both in linear tracks in the fixed disc, and in a common elliptic or otherwise closed shaped track in the rotating disc. In other embodiments tracks may be substituted for by raised edges where roller or slide bearings contact the sides of the edges.